1. Field of the Invention
The present invention relates to an indication input signal processing system in a remote controlled station for use in a remote supervisory control apparatus and more particularly, it relates to an indication input signal processing system suitable for a remote controlled station which is constituted by a digital processing unit.
2. Description of the Prior Art
In a remote supervisory control system, for the purpose of supervising or controlling the operation of various machines and apparatus equipped in an unattended remote controlled station such as for example a substation, the operation of the various machines and apparatus is observed in terms of an indication input signal standing for the state of relay contacts, the indication of meters and the like, and this indication input signal is transmitted to a centralized control station, i.e., a master station to energize a corresponding indication lamp on a control panel located in the centralized control station.
In general, the indication type used in a remote supervisory control apparatus is classified into four standard types (for example, reference is made to remote supervisory control apparatus for centralized control itemized in Japan Electric Machine Industry Association Standards) and corresponding thereto, the following three indication input types are available.
Indication type A: a momentary input having a duration of more than 50 ms is memorized in a memory and the memory is reset by an indication reset signal a from a master station;
Indication type B: a momentary input having a duration of more than 50 ms is memorized in a memory and the memory is automatically reset by an indication reset signal b provided from a remote controlled station after the momentary input has been sent by way of a cyclic digital transmission system to the master station with repetition of a predetermined cycle, that is, within a predetermined time period; and
Indication type C: an indication signal taken up by an indication input circuit is directly sent to a master station without any reset.
Indication type A is usually applicable to observe the operation of circuit breakers, being tripped or re-closed, and the transmission of the indication reset signal a to the remote controlled station is effected manually after an operator belonging to the master station has checked the indication input signals. In other words, this indication type is employed for relatively highly-weighted important indication input signals which require "check" by the operator. Indication type B is usually applicable to observe an indication input signal representative of an abnormal state of the machine and apparatus equipped in the remote controlled station, which abnormal state is detected by an abnormal detecting relay, for example. This indication input signal from the abnormal relay is sent to the master station with repetition of a predetermined cycle, that is, within a predetermined time period so as to enable indication lamps on the control panel in the master station for a predetermined time period. Then, irrespective of the fact whether or not the lamp indication is checked by the operator, the remote controlled station itself provides a reset signal b by which a memory circuit of the remote controlled station is reset. As will be appreciated from the above description, this indication type B is employed for indication input signals of relatively low-weighted importance which do not require "check" by the operator.
Indication type C is used for observing an indication input signal representative of the state of a switch, for example, wherein such an indication input signal obtained through a relay contact or the like element disposed in the remote controlled station is sent to the master station as it were, without being subjected to reset.
The operation of various machines and apparatus equipped in the remote controlled station is represented in terms of the operation of relay contacts, meter and the like, and as to each of the data signals (referred to hereinafter as position data signals) obtained through the relay contacts, a predetermined one of the three indication types is selected in accordance with a predetermined weight of importance of the operation of and supervision for the machines and apparatus, that is, weight of importance of the position data signal. An indication type selected for (or assigned to) one position data signal is not retained unchangeable permanently but must be exchanged with other indication types in conformity with the alternation of the control mode.
A prior art selection system for selecting one indication type for the indication input signal, that is, position data signal from the remote controlled station, which system corresponds to an indication input signal processing system referred to herein, was constructed as shown in FIGS. 1 and 2.
As shown in FIG. 1, contact information representative of the state of the machines and apparatus is taken up by indication input circuits 50 and 51 through auxiliary relay groups 60 and 61 which are electrically isolated from the machines and apparatus. Namely, the machine and apparatus contact information in terms of the on-off state of the auxiliary relay is taken up by the respective indication input circuits 50 and 51. These indication input circuits 50 and 51 take up input data signals while selecting one of the three indication types as described above. Outputs of the indication input circuits 50 and 51 in the form of indication signal groups each containing 10 position data signals, for example, are taken up by a collection circuit 40 which is well known in the art under the command of a transmission control circuit 20 (instruction route is not shown in the drawing) and then stored in a register 30 temporarily. The indication input signal thus stored temporarily is the converted into a predetermined transmission format, for example, of a cyclic digital transmission type by the transmission control circuit 20, which is well known in the art, and delivered from the transmission control circuit in the form of a serial signal. This output signal is modulated by a transmission unit 10 which is also well known in the art and transmitted onto a transmission line connected to the master station. One position data signal may be represented by one bit and one word containing 10 bits, for example, may preferably be transmitted.
Specifically, one of the indication input circuits for selecting the type of indication input signal, for example, indication input circuit 50 has a construction as shown in FIG. 2.
Assuming now that the auxiliary relay group 60 has 10 input lines (1, 2, . . . , 10) connected with various machines and apparatus in the remote controlled station, the number of auxiliary relays to be interposed in the ten input lines amounts to ten. The indication type of contact information (position data signals) from the respective auxiliary relays is selected and set as to each one of the position data signals as will be described later with reference to FIG. 2. In FIG. 2, memory circuits 501-1 and 501-2 adapted to select the indication type A are set by receiving a momentary input having a duration of more than 50 ms and reset by an indication reset signal a, whereas memory circuits 502-1 502-2 adapted to select the indication type B are set by receiving a momentary input having a duration of more than 50 ms and reset by an indication reset signal b after the content of the memory circuits 502-1 and 502-2 has been sent by way of a cyclic digital transmission system to the master station with repetition of a predetermined cycle, that is, within a predetermined time period. Taking input line 1, for example, one output is selected and delivered from the indication input circuit 50, which output corresponds to either output c from the memory circuit 501-1, output d from the memory circuit 502-1 or output e directly representative of the state of a relay in the auxiliary relay group 60. Specifically, as viewed from FIG. 2, a position data signal fed from the input line 1 is assigned with the indication type B and a position data signal fed from the input line 2 is assigned with the indication type A. Conventionally, the memory circuits 501-1, 501-2 and 502-1, 502-2 are constituted by electromagnetic relays and the selective connection of the output signals c, d and e is effected by means of a mechanical transfer switch or by exchanging fixed connections.
With the prior art system described above, however, the individual memory circuits 501-1, 501-2 and 502-1, 502-2 are provided for each one of the position data signals so that as the number of indication input signal increases, not only is the hardware greatly increased but also the number of relays which are not in use (memory circuits 501-1 and 502-2 in FIG. 2) is also increased, thereby impairing the production of an inexpensive apparatus.